Components with a spherical, hemispheric, hemispherical shell, columnar or tubular shape, or any other irregular shape are widely used in all kinds of fields. In most applications, the components are not only required to have good properties of wear-resistance, corrosion-resistance and heat-resistance, high-precision of dimensional coordination and smooth finished surface, but also have high obdurability, mechanical bearing capacity, and machinability. The common components may include an artificial femoral ball head in total hip arthroplasty components, an artificial acetabulum with a hemispherical shell shape, a plunger with a columnar shape, a ball valve body with a tubular shape, and an irregular femoral condyle prosthesis, i.e. prosthetic knees, and so on.
Ceramic material has characteristics of high surface hardness, wear-resistance, and corrosion-resistance. However, it has low flexural strength and low fracture toughness with bad mechanical bearing capacity. Components made of ceramic material are more likely to crack brittlely, therefore can not be used to manufacture the above mentioned components individually. In the existing techniques, composite toughening ceramic emerges to improve fracture toughness of the common ceramic. However, composite toughening ceramic, despite its high fracture toughness, has some drawbacks compared with the common ceramic. For example, alumina ceramic with introduction of zirconium dioxide (ZrO2) has its surface hardness and compression resistance strength to be lowered. Ceramic with introduction of whisker or fiber has its density and wear-resistance property to be decreased.
To solve above problems, there appears, in the existing techniques, a shell-core structural component which includes a shell layer of ceramic and a core layer of metal, by forming a ceramic film on the surface of a metal using all kinds of physical or chemical methods, so as to increase wear resistance, corrosion resistance and heat resistance of the component. The shell-core structural component has a metal core, and it has excellent flexural strength, and high fracture toughness and machinability, which thereby is not likely to crack. In addition, the shell-core structural component has a ceramic shell, it has high surface hardness, and good wear resistance, corrosion resistance and heat resistance. That is, the shell-core structural component combines advantages of both metal and ceramic. Usually, the above-mentioned ceramic film is formed using a physical or chemical deposition. However, the ceramic film formed by these methods are thin in thickness, ranging from several micrometers to tens of micrometers, weak in adhesive strength between the shell layer and the core layer, poor in mechanical bearing capacity, and poor in durability and stability of wear-resistance and corrosion-resistance.
In order to increase the thickness of the ceramic shell layer and adhesive strength between the shell layer and the core layer, there provides three methods in the existing technology and will be described below. The first method may include: mixing ceramic powder, metal powder, and compound powder having different proportions of ceramic powder and metal powder, with organic carrier to obtain a slurry with a certain solid loading; tape casting, stacking and cold pressing to form a green body of a multilayer shell-core composite structural component having a shell layer, a transition layer, and a core layer; and sintering the green body to obtain a multilayer shell-core composite structural component. The second method may include: dry powder cold pressing repeatedly on ceramic powder, metal powder and compound powder having different proportions of ceramic powder and metal powder, to form a green body of a multilayer shell-core composite structural component having a shell layer, a transition layer and a core layer; and sintering the green body to obtain a multilayer shell-core composite structural component. The third method may include: mixing ceramic powder, metal powder and compound powder having different proportions of ceramic powder and metal powder with a solvent like deionized water to obtain a suspension liquid with a certain solid loading; electrostatic depositing on the suspension liquid in multiple steps to obtain a green body of a multilayer shell-core composite structural component having a shell layer, a transition layer and a core layer; and sintering the green body to obtain a multilayer shell-core composite structural component. However, the above mentioned methods have following disadvantages, such as hard to form an irregular shape, layers in high and even thickness, and hard to accurately control the thickness of each layer, and microstructure and performance of the multilayer shell-core composite structural component. Thus, it is difficult to apply the existing methods to form a multilayer shell-core composite structural component required in this disclosure. That is, using the existing methods, it is difficult to obtain a multilayer shell-core composite structural component having high surface hardness, high wear resistance, corrosion resistance and heat resistance, high adhesive strength between the shell layer and the core layer, good mechanical bearing capacity, high fracture toughness, and high matching ability and stability of performance.